1. Field of the Invention
The present invention relates to a slat rotation, slat winding and unwinding control device of window blind, more particularly to a slat rotation, slat winding and unwinding control device of window blind in which the base can be easily assembled, no limitation is placed upon the winding direction of the pull cord on the cord spool, and either a connecting strap or a connecting string is easily to be fixed on a housing member.
2. Brief Description of the Prior Art
Ordinarily, conventional control device for controlling the opening-closing of slats and lifting or lowering of a window blind are shown in FIG. 8, a perspective exploded view of the structure of the control device; and in FIG. 9, a sectional view of the assembly of the structure of the control device. The control device (7) is mainly formed by a base (71), a fitting member (72), a cord spool (73), a housing member (74), and a rotation member (75). The fitting member (72) is fixed at one end of the base (71), and a pivot hole (711) is formed at the other end of the base (71). A threaded section (721) is formed inside the fitting member (72), which is in threading engagement with the cord spool (73). The cord spool (73) has threading grooves (731) formed on its outer edge, the threading grooves (731) being in threading engagement with the threaded section (721) of the fitting member (72). An aperture (732) is further provided at the outer edge of the cord spool (73) for fixing one end of a pulling cord (733) so that the pulling cord (733) can be wound around the outer edge of the cord spool (73). A flange stopper (734) is formed at the end of the cord spool (73) for preventing the cord spool (73) from swinging out beyond the fitting member (72) to fall off. The housing member (74) is fitted on the base (71) to form correspondingly an accommodation for the fitting member (72) and the cord spool (73). A cavity section (741) is formed at the bottom end face of the housing member (74) so as to house the fitting member (72) and the cord spool (73) therein. A pivot shaft (742) corresponding to the pivot hole (711) of the base (71) is provided at one side of the housing member (74). Further, a locating recess (743) is provided at the top end of the housing member (74), and two locating holes (744) are provided in the locating recess (743). A connecting strap (76) for connecting each slat of the window blind is wound around a locating bar (761) first, and then the strap with the locating bar is placed within the locating recess (743), finally fixing screws (745) are threaded into the locating holes (744) so as to fix the connecting strap (76) with the locating bar (761) in place. One end of the rotation member (75) is to fit with the pivot shaft (742) of the housing member (74). A torsion spring (751) is fitted over the outside of the rotation member (75) which is pivotally disposed within the pivot hole (711) of the base (71). An aperture (752) for fitting with a bracket rod is provided at the outer end face of the rotation member (75) in such a manner that the control device (7) after assembly can be fitted inside from the lateral side of the Upper beam (8) of the window blind for further combination, and the aperture (752) provided at the outer end face of the rotation member (75) is fitted with the bracket rod (81) of the upper beam (8). In this manner, when the rotation member (75) rotates the housing member (74) so as to move the connecting strap (76) (ladder string), so that all slats (77) in unison can rotate an angle to open or to close and the pulling cord (733) wound on the cord spool (73) can be wound or unwound to control the lifting or lowering of the window blind.
Although the above control device can control the opening or closing of each slat and the lifting or lowering of the window blind, however, some drawbacks has been found in practical implementation.
1. The base of the control device can only be fitted inside from the lateral side of the upper beam of the window blind for further combination. If the width of the window blind is wider, i.e., the support rod is longer, it is difficult to fit the control device into the upper beam.2. A flange stopper is formed at the end of the cord spool for preventing the cord spool from swinging out beyond the fitting member to fall off. So, when the cord spool is rotated to the end in one direction, a big impact force will be produced if force continues to be applied. In this case, the cord spool is blocked by the flange stopper and is unable to continue the rotation, so the cord spool only can rotate back in reverse direction. This may result in limitation on its usage and thus may cause inconvenience.3. The connecting string for connecting each slat of the window blind has to be wound around the locating bar and then placed in the locating recess at the top end of the housing member and finally is fixed in the locating hole of the locating recess so that the connecting string with the locating bar is fixed in place. It seems the process is troublesome and inconvenient.